The present invention is related to a portable terminal having a position detecting function, a location calculating server apparatus having a position detecting function, and a service provider""s server apparatus for providing information in response to a location of a portable terminal.
As one of information communication services with employment of mobile terminals, information may be provided in response to positions, or locations of these portable terminals. Specifically, information as to restaurants located in the vicinity of these mobile terminals may be provided, a time table of a station located at the nearest position with respect to a mobile terminal may be displayed, and a navigation service up to a destination place may be provided.
As such a position detecting method executed by way of a mobile terminal, JP-A-7-181242 (laid-open on Jul. 21, 1995) describes the position detecting apparatus with employment of the cellular wireless base station. In this position detecting apparatus, a mobile terminal firstly receives the signals which are transmitted from a plurality of wireless base stations. Then, the position detecting apparatus calculates a distance between the wireless base station and the mobile terminal based upon propagation delay of the signals so as to detect the position of the mobile terminal. A remarkable improvement is made in such position detecting techniques with employment of wireless base stations. The article xe2x80x9cPositioning Cellular Phone without GPSxe2x80x9d on page 1 of The Nikkei Business Daily issued on Mar. 16, 2000 describes that the error in the position detecting operation may be limited into a range of 10 meters.
Also, another method for detecting a position of a mobile terminal has been proposed, while a GPS receiver is built in this mobile terminal, and GPS electromagnetic waves transmitted from the GPS satellites are used. In this case, the mobile terminal firstly receives the GPS signals transmitted from a plurality of GPS satellites. This mobile terminal calculates both coordinate values of these satellites and propagation delay of the GPS signals based upon both orbit information and transmission time information of the satellites, which are contained in the received GPS signals. The position of this mobile terminal can be detected based on the above-calculated coordinate values and propagation delay.
Conventional mobile terminals having the above-described position detecting functions have been designed in such a manner that these mobile terminals may continuously detect the positions, or the locations of the own mobile terminals in high accuracy. However, these conventional mobile terminals do not own such a function capable of intentionally adjusting, or controlling positioning accuracy. As a consequence, it is practically difficult to change position detecting methods in accordance with required accuracy, while an attention is paid to utility of positional information. As a result, a first problem may occur. That is, while a provision of information made based upon a present position of a mobile terminal is accepted, in such a case that a detection error contained in a position detection result may give a small adverse influence to the provided information, one conventional position detecting method cannot be changed into such a simple position detecting method having a light load. For instance, when information as to movie theaters located within a circular range of 10 km is required while a present position of a mobile terminal is positioned as a center, there is no large difference between a content of positional information provided in the case that a position detecting operation is performed in such accuracy that a detection error is set to 50 meters, and a content of positional information provided in the case that a position detecting operation is carried out in such accuracy that a detection error is set to 100 meters. Under such a circumstance, if a position detecting method can be changed within such a range where there is no adverse influence in the provided positional information, then loads given to mobile terminals can be reduced and also power consumption thereof can be reduced, which may improve utility of users who use mobile terminals.
Also, as a second problem, the following difficulty may exist. That is, since such a conventional position detecting method can be made simpler, if necessary, a time duration required to detect a present position of a mobile terminal cannot be shortened, but also waiting time for a user of this mobile terminal cannot be reduced.
Furthermore, since time required to detect present positions is always constant in conventional mobile terminals, time periods during which position detecting operations are carried out are identical to each other irrespective of moving speeds of users of these conventional mobile terminals. However, position detecting time periods suitable for detecting present positions of these conventional mobile terminals will differ to each other, depending upon conditions of these mobile terminals. For example, in the case that an owner of a mobile terminal takes a train to be transported in a high speed, a positional change per one measuring time may become large, as compared with a positional change per one measuring time in such a case that this terminal owner is moved at the normal speed. As a result, a real-time characteristic of displaying of present positions of this mobile terminal may be improved if the time period for detecting the present positions of the mobile terminal is shortened so as to frequently detect these present position of this mobile terminal. Under such a circumstance, as a third problem, the following difficulty may exist. That is, for example, in such a case that an owner of a conventional mobile terminal is moved in a high speed, the real-time characteristic of the information as to the present positions of the conventional mobile terminals cannot be improved by changing the position detecting time duration in correspondence with this moving speed. With respect to such a mobile terminal which is moved in a high speed, if present positions of this mobile terminal are displayed by employing such a map whose range is made wider than the normal-ranged map, then the present positions of this mobile terminal can be readily grasped while reducing a total switching number of the normal-ranged maps. In this wide-ranged map case, even when positioning accuracy is not so high, these is a small adverse influence given to the results displayed on this wide-ranged map. As apparent from the foregoing descriptions, if the time duration for detecting the present position may be shortened and furthermore accuracy of the position detecting operation may be suppressed lower than the normal accuracy, then the real-time characteristic of the positional information of the mobile terminal could be improved without increasing the work load given to this mobile terminal.
In accordance with an aspect of the present invention, a means for solving both the first problem and the second problem may be realized by such a server apparatus which is equipped with both a function capable of changing a position detecting method in response to positioning accuracy which is instructed, and also, another function capable of instructing positioning accuracy with respect to a mobile terminal.
In accordance with another aspect of the present invention, a means for solving the third aspect of the present invention may be realized by both a mobile terminal which is equipped with a function capable of setting positioning accuracy and also a function capable of either setting or automatically recognizing a present move speed of the mobile terminal, and may be realized by such a server apparatus which is equipped with a function capable of instructing both a position detecting time duration and positioning accuracy with respect to the mobile terminal.
A terminal, according to an embodiment of the present invention, is provided with a reception unit for receiving signals which are transmitted from a plurality of signal generating sources; and a positioning unit for performing a position detecting operation based upon propagation delay time of the received signals, in which the positioning unit executes a position detecting operation by way of a positioning method in accordance with the variably set accuracy. The accuracy of the position detecting operation is determined in connection with a service provided by employing the terminal.
A position detecting function of the above-described terminal may be realized by a semiconductor device mounted on the terminal. The semiconductor device is provided with a propagation delay measurement unit and a position calculation unit. In the semiconductor device, a position detecting operation is carried out, while a total number of generating sources for signals whose propagation delays are measured, a time duration used to measure the signals, a calculation method, and position calculation completion criteria are changed based upon designated accuracy of the position detecting operation.
A service provider""s server apparatus, according to another embodiment of the present invention, is comprised of a table which describes a correspondence relationship between plural sorts of services and accuracy of position detecting operations, and the service provider""s server apparatus instructs a terminal to perform the position detecting operation in accuracy corresponding to a requested service. Then, this service provider""s server apparatus provides a service based upon a received detection result. Alternatively, the service provider""s server apparatus may instruct the accuracy of the position detecting operation to the terminal, while employing a total number of signal generating sources, a measurement time duration of signals, a total sampling number used for averaging operation, position calculation completion criteria, and so on.
The technical scope/spirit of the present invention may cover such a method of providing a service by utilizing a terminal position. That is to say, while a position detecting operation executed in accuracy in accordance with a sort of service is instructed, the service is provided based upon the result of this position detecting operation.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.